/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.code.motoo.filter;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * 
 * @author linfengqi
 * @version 1.0  May 11, 2009
 */
public class DefaultFilterChainBuilder implements FilterChainBuilder{
	
	private final List<Filter> list;
	
	/**
     * Creates a new instance with an empty filter list.
     */
    public DefaultFilterChainBuilder() {
        list = new CopyOnWriteArrayList<Filter>();
    }
    
    public synchronized void addFirst(Filter filter) throws Exception {
        register(0, filter);
    }

    /**
     * @see IoFilterChain#addLast(String, IoFilter)
     */
    public synchronized void addLast(Filter filter) throws Exception {
        register(list.size(), filter);
    }

    private void register(int index, Filter e) throws Exception {
        if (contains(e)) {
            throw new IllegalArgumentException("the filter is already exist ");
        }
        
        e.init();
        list.add(index, e);
    }
    
    public boolean contains(Filter e) {
        return list.contains(e);
    }

    /**
     * Creates a new copy of the specified {@link DefaultIoFilterChainBuilder}.
     */
    public DefaultFilterChainBuilder(DefaultFilterChainBuilder filterChain) {
        if (filterChain == null) {
            throw new NullPointerException("filterChain");
        }
        list = new CopyOnWriteArrayList<Filter>(filterChain.list);
    }

	public void buildFilterChain(FilterChain chain) throws Exception {
		if (!(chain instanceof DefaultFilterChain)) throw new IllegalStateException("Current filter chain is not a DefaultFilterChain.");
		DefaultFilterChain defaultChain = (DefaultFilterChain) chain;
		for (Filter filter : list) {
			defaultChain.addFilter(filter);
        }
	}

}
